As for voting, parties will release manifestos during elections which are publicly available. These outline policy, ambitions, etc. Of course, it's important to read with a critical eye, but it would certainly give you a better idea of what the party is standing for.
More generally it may help to understand where parties fall on a political spectrum. While resources like the manifesto change frequently depending on the party leadership's approach, it's a good foundation to understand what right and left-wing mean and what that, on an incredibly rudimentary basis, entails for their ideology.
If you aren't out to absorb information rapidly, just read the news. You'll pick useful pieces of political information simply by keeping up to date.
If you can't be bothered to do any of those, just take my totally, un-biased opinion and vote Conservative.
-Googling can help you out with the gist of how the election actually works and how parliament functions
-Each party will have manifestos kicking about. Their websites will explain the gist of what they're 'currently' about. Best time to look is close to the elections cause that's when they release new manifestos with all the most recent promises n stuff in.
-Keeping up to date with the news is generally a brilliant way of absorbing information - smth like the BBC news app is great for quickly getting the gist of everything going down.